Radon Mitigation in St. Paul, MN

A City on the Bluffs

Downtown St. Paul and much of the city along the Mississippi stand on a thin cap of Platteville limestone over soft St. Peter sandstone — the sandstone the city's caves along the West Side and Wabasha Street are cut into. Away from the river the bedrock is buried under glacial deposits. Fractured limestone and loose sandstone give soil gas easy routes, so houses near the bluff line — Dayton's Bluff, the West Side, the edge of Summit Hill and Highland — can read high without anything unusual about the house itself.

Limestone Foundations

St. Paul's older houses were frequently built on foundations of local limestone laid in lime mortar. Those walls are porous along their entire height, and the mortar has usually softened over a century. Soil gas comes through the walls as well as the floor. Mitigating these houses leans heavily on sealing — pointing the worst joints, sealing the floor-to-wall line and sometimes parging — and occasionally needs more than one suction point to hold a pressure field in a basement that leaks on every side.

From Summit Avenue to the East Side

The housing covers more than a century. Victorian and Queen Anne houses on Summit Hill and Dayton's Bluff sit over tall stone basements. The 1910s–20s bungalows and foursquares of Mac-Groveland, Highland Park, Como and Hamline-Midway have lower basements, often with a single floor drain. The East Side and the edges of the city fill in with post-war ramblers on block walls. Each generation leaks soil gas differently, and no single approach fixes all of them.

Keeping the Pipe Inside

Many St. Paul owners do not want a white pipe up the front of a historic house, and in a St. Paul winter an exterior pipe is also the one most likely to freeze. Where the house allows, we route through a back stair, a closet stack or a chimney chase into the attic, with the fan in the attic. It costs more than an outside riser and it keeps the house looking the way it should.

Working Across St. Paul

We cover the whole city. Start with a 48-hour test in the basement. If it is high, a sub-slab system built around the foundation you actually have, with the walls and drains sealed, brings it down — and a retest proves it.

St. Paul Radon FAQs